fix(audio): restore msg binding in DecodeError arm, use SlidersVertical for EQ icon

- Revert _msg → msg in DecodeError match arm; the variable is used in the
  debug_assertions eprintln! block so the underscore prefix caused a compile error
- Replace SlidersHorizontal with SlidersVertical (lucide-react) in PlayerBar,
  LiveSearch, and AdvancedSearch so the EQ/filter icon shows vertical bars

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src-tauri/src/audio.rs

@@ -1149,7 +1149,7 @@ impl Iterator for SizedDecoder {
                         self.current_frame_offset = 0;
                         break;
                     }
-                    Err(symphonia::core::errors::Error::DecodeError(ref _msg)) => {
+                    Err(symphonia::core::errors::Error::DecodeError(ref msg)) => {
                         self.consecutive_decode_errors += 1;
                         // Log sparingly: first drop, then every 10th to avoid spam.
                         #[cfg(debug_assertions)]